Existing camera systems include features to track the pose of a camera. The pose may comprise the position of the camera, orientation of the camera or both.
Known technologies for monitoring or tracking the position of a camera use dead-reckoning techniques. These provide an incremental measurement of pose, based on an initial absolute pose reference. However, these are prone to error, which accumulates over time. This error can have a significant effect.
In a Virtual Reality system, the image taken by the camera is combined with virtual image to generate an output image. The accumulated error would manifest itself as a misalignment between the camera-generated image and rendered virtual image when the two are combined.
In a robotic camera motion control system this error would manifest itself as a framing error. In other words, the instruction provided by the camera controller would be based on an incorrect estimated position for the camera and result in an incorrect movement.
An absolute pose measurement technology for the camera would be advantageous. It would be desirable for absolute pose measurement to replace the incremental dead-reckoning. However, existing absolute pose measurement systems do have some disadvantages that preclude this. Some absolute pose measurement systems are incapable of delivering a sufficiently high update rate required for camera motion tracking and control systems. Also, absolute pose measurement systems that use reference targets can have problems when the targets are occluded by other items. In such case, the absolute pose measurement system is unable to determine the pose of the camera at all. Moreover, an absolute pose measurement system working independently of any odometric dead-reckoning system can also exhibit significant jitter.